


three parts of one whole

by moonlightcanary



Category: Shadowhunters (TV)
Genre: Bisexual Jace Wayland, Elaine is completely lost, F/M, M/M, Maia is also bisexual, Meeting the Family, Multi, Pansexual Simon Lewis, Polyamory, Rebecca is just trying to be a Good Sister, not exactly how Simon had hoped to do so
Language: English
Status: Completed
Published: 2017-07-02
Updated: 2017-07-02
Packaged: 2018-11-22 07:17:30
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,021
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11375271
Author URL: https://archiveofourown.org/users/moonlightcanary/pseuds/moonlightcanary
Summary: Rebecca wouldn’t consider herself the typical ‘over protective older sibling’ type, but that didn’t make her any less weary of those who dated her little brother. Someone had to look after him.And that’s what she was doing when she introduced herself to the mysterious tattoo covered blonde dude who was sitting front row at Simon’s one-man-band concert, watching Simon like he was the only person in the world that mattered.





	three parts of one whole

**Author's Note:**

> an anon on Tumblr requested a jacemaiasimon prompt where jace and maia meet simons mom and sister. so here it is.

Rebecca wouldn’t consider herself the typical ‘over protective older sibling’ type, but that didn’t make her any less weary of those who dated her little brother. Someone had to look after him.

And that’s what she was doing when she introduced herself to the mysterious tattoo covered blonde dude who was sitting front row at Simon’s one-man-band concert, watching Simon like he was the only person in the world that mattered. 

Rebecca sat down next to him, waiting a minute before speaking. “You know him?” 

The guy glanced at her briefly, his eyes returning to Simon. “Yeah, uh, you could say that. You?”

Rebecca debated her words for a second. “I’m his sister.” 

That brought his attention to her. His eyes finally completely focusing on her. It was then she noticed the brown mixed in with the blue in his left eye. 

“You’re Rebecca.” 

It wasn’t a question. 

“And you are?” Rebecca asked, trying to get her footing back in the conversation.

His eyes searched her before going back to watching Simon. “I’m Jace.” 

Rebecca felt like that was supposed to explain something. “He’s never mentioned you before.” 

“Figures.” Jace said, not even glancing at her. 

Rebecca had no idea what that meant. “How’d you two meet?”

“It’s a long story.”

Rebecca frowned, she couldn’t figure this Jace guy out. “Right... uh, what is he to you? I mean, the way you look at him... Are you guys like... a _thing_?”

Jace turned his attention back to her. “You should really ask him.” 

Rebecca wasn’t one to back down that easily. “But... you do- you do like him though? _Romantically_?” 

Jace crossed his arms, and for a second Rebecca thought he was gonna get up and walk away. But his expression softened. 

“I-” Jace sighed. “Yeah.” 

Rebecca wanted to ask him more questions, to try and find out why Simon had never mentioned him before, but before she could, his phone buzzed. 

Jace glanced at his phone. “I gotta take this.” 

And just like that he slipped off, disappearing into the crowd. 

Rebecca sighed, slumping back in her chair. 

~

“I think Simon has a boyfriend.” Rebecca announced to her mother. 

“What makes you think that?” Elaine asked with a raised eyebrow. 

“I was talking to this guy- Jace, just before intermission, and the way he was staring at Simon-” Rebecca paused. “I tried to ask Jace if they were dating but he just deflected saying that I should ask Simon- but he does have feelings for Simon! He told me so.” 

“Just because Simon’s pan and someone in the audience says they have a crush on him doesn’t mean that they’re dating, Becca.” Elaine pointed out. 

Rebecca shook her head. “He wasn’t just _someone in the audience_. They know each other. And I’m telling you- there’s _something_  between them.” 

Elaine glanced over at Simon, who was currently in a deep conversation with his best friend, Clary. “Well, we will just have to ask Simon about this Jace, and invite him over to dinner one night so I can meet him.” 

“Yeah... Wait, actually, I think that’s him over there.” Rebecca said, pointing over to the bar where Jace was stood talking to a bartender. 

Elaine tried to follow Rebecca’s gaze. “Really? Where? What does he look like?” 

“The blonde by the-” Rebecca froze. “What the _hell_?”

“What? What is it?” Elaine asked, glancing nervously at her.

Jace had kissed the bartender. He had _kissed_  her. And it looked like she kissed back, for a moment, before she pushed him back and muttered something, nodding in the direction of Simon, and Jace had rolled his eyes. 

“Oh my god.” Rebecca muttered, Jace was _cheating_  on Simon. He was _cheating_  on her _brother_.

“ _What_?” Elaine repeated.

Rebecca didn’t respond, her rage bursting out as she stormed over to Jace. “You fucking _bastard_! I thought you fucking cared about him!” Rebecca shoved the startled Jace backwards. “You sat there letting me believe that you _cared_  about him! Staring at him with stars in your fucking eyes! But you- you’re a  _cold,_   _cruel_ -”

“Woah, woah!” Simon exclaimed, appearing between Rebecca and Jace at lightning speed. “Bex, what the hell are you doing?” 

“What am _I_  doing?” Rebecca sneered at Jace. “Why don’t you ask your _boyfriend_  what he was doing kissing that bartender?” 

Rebecca jerked her head in the direction of said bartender, who was- who was _laughing_. 

“I’m sorry, do you find this _funny_?” Rebecca demanded.

“Woah, Bex,” Simon put a hand on her shoulder. “Bex, calm down. Jace isn’t cheating on me with Maia.”

Rebecca stared at Simon, he was way too calm for this situation. “But- but I saw him kissing her.” 

“That’s ‘cause he did.” The bartender- Maia- said. 

Rebecca had never been so lost, she glanced to her mother, who looked just as lost. 

Simon ran a hand through his hair. “This- this isn’t exactly- this isn’t at all how I had imagined you guys meeting. But uh... Mom, Bex, meet Jace and Maia, my, uh, my boyfriend and girlfriend.” 

Rebecca was pretty sure her brain short-circuited. “Boyfriend... _and_  girlfriend?” 

Simon bit his lip. “Uh... yeah. Yes. We are all dating each other.”

“Oh. Uh, alright.” Rebecca wasn’t sure what else to say. She glanced to her mother, whose expression was damn near impossible to read. 

“Mom...?” Simon’s voice was barely above a whisper. 

“I...” Elaine began, slowly gathering her thoughts. “I’m... I’m not going to pretend that I- _get_  this... But... I love you, monkey, and if they make you happy... Well, that’s all that matters, right?”

Simon’s face broke out into a grin, surging forward and attacking his mother with a hug.

Rebecca turned to Jace. “Uh, sorry for, uh, accusing you of cheating. I- I had no idea...”

Jace laughed. “I’ve been accused of worse. Plus I would’ve done the same thing if it was one of my siblings... Thanks for being cool about this- _us_.” 

Rebecca shrugged, glancing between Jace and Maia. “As long as you don’t hurt him, I think we’ll be fine.”

 

Okay, maybe she was a _little bit_  and over protective older sibling.

**Author's Note:**

> I came up with this idea in the shower and honestly I think it turned out pretty decent??   
> please let me know ur thoughts by leaving kudos + comments <3


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